The invention pertains to a towed implement with an undercarriage, at least one wheel suspension, a spring member and an adjusting device.
DE-A-31 39 936 discloses a towed agricultural implement with an undercarriage, on the two lateral end regions of which one respective wheel suspension is arranged. Both wheel suspensions include a shaft in the region of their pivoting axis, and these shafts are connected such that they can be moved relative to one another by means of a spring-loaded, transverse swinging arm, namely on the ends that face one another. An adjusting device can be engaged with limit stops on the wheel suspensions in one direction in order to adjust the wheel suspensions in one direction.
EP-A1-0 149 870 discloses a towed mower in which an adjusting device and a spring member are connected in series. In one of the embodiments described in this publication, an adjusting cylinder acts upon a pivoted shaft that vertically pivots the wheel cranks on the respective end regions by means of braces in the form of gas springs formed by hydraulic cylinders coupled with gas accumulators.
The known suspension arrangements exhibit a problem which occurs when the mower encounters an obstacle, namely that the spring members need to absorb much energy and, after overcoming the obstacle, abruptly release the stored energy in case of low counter forces, for example when the wheel raises off the ground. This can lead to damage to the adjusting device, wherein the piston may, in particular, impact on the end of the cylinder housing or an inside shoulder and/or undergo damage to the sliding surface or the seals.
According to the present invention there is provided an improved suspension arrangement for a towed implement.
An object of the invention is to provide a suspension arrangement for a towed implement wherein provision is made for damping the rebound of the stored energy so as to prevent damage to the hydraulic or pneumatic actuators.
A more specific object of the invention is to provide a suspension for a towed implement including damping arrangements using coil or disc springs, gas pressure reservoirs or rubber-like elements.
Yet a more specific object is to provide a suspension, as set forth in the foregoing objects, wherein the damping arrangements may include devices that are relatively inexpensive and readily available on the market such as a coil spring or disk spring that is arranged around a piston rod in a cylinder housing, or a caoutachouc mass in the form of a ring or the like could be inserted between the end of the cylinder housing and the piston; and/or a gas pressure reservoir could be connected to a second piston chamber.
Yet another object of the invention is to provide a second embodiment wherein the wheel suspension includes a reversing link which operates when pivoted in a first direction to direct forces such that a gas spring accumulator that is coupled to a hydraulic cylinder connected to the reversing link acts so as to cushion loads caused when the wheel passes over an obstacle and, when pivoted in a second direction by the force of a suspended wheel returning to its operating position, also acts to cushion this movement of the wheel.
These and other objects will become apparent from a reading of the ensuing description together with the appended drawings.